Web: visual design pass (issue #26)

Addresses the screenshot-review feedback in #26. No framework or build
step added — all of this stays within the existing plain HTML/CSS/
vanilla-JS + go:embed architecture.

- Nav: re-enable the bottom tab bar that was already built and
  switched off (Queue/On-call/Alerts/Team + a "More" sheet for
  Stats/Admin/Account), replacing the hamburger on phone width.
- Queue: chip counts, a scroll fade on the filter row, a
  "Triggered Xh ago" + severity label per row, a chevron on the team
  switcher so it reads as a dropdown.
- On-call: collapse repeated same-person days into shift bars (week
  view and "your shifts" both), show the week as a date range with
  the ISO week number as secondary text, split "Current shift" out
  from "Next shifts" with "ends in Nd", a pill badge + row highlight
  for "you".
- Incident detail: fix the actual bug behind the duplicate
  "acknowledged" timeline entries (acknowledgeIncident's UPDATE had no
  guard on the incident's current status, so acknowledging an
  already-acknowledged incident silently re-logged the event — now
  idempotent, with regression tests on both the authenticated route
  and the ntfy ack-button route). Relabel escalation re-pages so they
  don't look like the same page landing twice. Copy the primary action
  up near the top. Label the "···" button. Group the timeline by
  phase (triggered/acknowledged/resolved). Add an "at a glance"
  summary row (duration/severity/responsible) and collapse the group
  labels by default.
- Team overview: reword the vague copy ("One owner." etc.) into plain
  labels.
- Empty states: fill in missing icons/one-liners across queue,
  alerts, stats and the incident timeline.
- CSS: fix card padding bugs, verify link contrast already passes AA,
  introduce a --fs-* type-scale token set and migrate the few
  genuinely isolated cases onto it (left sizes tied to a fixed shape,
  a deliberately prominent display, or a non-negotiable constraint
  like the iOS-zoom-prevention input size as documented exceptions
  rather than guess at a render this change can't see).

Verified with the full fmt/lint/test/helm-lint gate, plus a live
instance against the test DB with seeded incidents and schedule data
to trace the on-call grouping and timeline phase-splitting logic
against real API responses.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

internal/web/static/js/team.js

@@ -182,7 +182,7 @@ function subnav() {
 // to the global team selector in the nav, which is what onTeamChange above
 // reacts to.
 function teamPicker() {
-  return h('div', { class: 'card' }, h('h2', { text: data.team.name }));
+  return h('h1', { class: 'detail-title', text: data.team.name });
 }
 
 // --- overview --------------------------------------------------------------
@@ -204,18 +204,18 @@ function overview() {
     menuCard('/team/rota', 'Rota', null,
       onToday ? `${onToday.username} is on call today.` : 'Nobody is on call today.'),
     menuCard('/team/members', 'Members', (data.members || []).length,
-      owners === 1 ? 'One owner.' : `${owners} owners.`),
+      owners === 1 ? '1 owner, full access.' : `${owners} owners, full access.`),
     menuCard('/team/escalation', 'Escalation', levels || null,
       levels
-        ? `${levels === 1 ? 'One level' : `${levels} levels`}${data.escalation.fallback_topic ? ', then a fallback topic.' : '.'}`
+        ? `${levels} escalation level${levels === 1 ? '' : 's'}${data.escalation.fallback_topic ? ', then a fallback topic.' : '.'}`
         : 'No ladder — nobody but the first person is woken.'),
     menuCard('/team/sources', 'Alert sources', keys || null,
       keys
-        ? (unused ? `${unused} of them never used.` : 'All in use.')
+        ? (unused ? `${unused} of ${keys} never used.` : `${keys} key${keys === 1 ? '' : 's'}, all used recently.`)
         : 'No key yet, so nothing can reach this team.'),
     menuCard('/team/deadman', 'Dead man’s switches', switches || null,
       switches
-        ? (dead ? `${dead} of them silent.` : 'All quiet, as they should be.')
+        ? (dead ? `${dead} of ${switches} silent.` : [icon('checkCircle', 'icon overview-note-icon'), ' Dead man’s switch: healthy.'])
         : 'Nothing watched.'),
   );
 }